1. Field of the Invention
The present invention relates to a non-glare film and a polarizing device to be preferably used on the surface of a high-resolution image display such as a cathode ray tube (CRT), a liquid crystal panel and the like to be used in an image display of a word processor, a computer, a television and the like, and a display device using the same non-glare film or polarizing device.
2. Related Art
In a display as described above, when a light emitted mainly from the inside comes straight on without diffusing on the display surface, a viewer of the display surface feels dazzling. In order to prevent this, the display surface is provided with a non-glare film for diffusing a light emitted from the inside to some degree. Such a non-glare film is formed by coating the surface of a transparent base film with a resin containing a filler such as silicon dioxide (silica) and the like, as disclosed, for example, in Japanese Patent Laid-Open Publication No. Hei 6-18706, Japanese Patent Laid-Open Publication No. Hei 10-20103 and the like.
These non-glare films include a type of forming a rugged shape on the surface of a non-glare layer by cohesion of particles of cohesive silica and the like, a type of forming a rugged shape on the surface of a layer by adding into a resin an organic filler having a particle diameter larger than the thickness of a coating film, and a type of transferring a rugged shape by laminating a rugged film onto the surface of a layer.
Any type of conventional non-glare films as described above obtains a light diffusing and glare preventing action by action of the surface shape of a non-glare layer and in order to enhance its glare preventing ability it is necessary to enlarge said rugged shape, but there is a problem that enlarging the ruggedness raises the haze value of a coating film and this causes deterioration in sharpness of an image.
As a film similar to the films described above, a light diffusion film obtaining a light dispersion effect by dispersing fine particles inside a layer has been disclosed in Technical Report MD-96-48 (1996), pp.277 to 282, of The Illuminating Engineering Institute of Japan, for example, as a film for a reflection-type liquid crystal display device.
In order to obtain a sufficient light diffusion effect from an internal scattering effect of a light diffusion film used here, the diameter of particles used needs to be made large, and doing so causes a problem that an area having a high haze value of the surface of a reflection-type liquid crystal display device is very poor in sharpness of an image.
And in case of using such a non-glare film obtaining a light diffusion effect by an internal scattering effect as said light diffusion film on the surface of a display, there is also a problem that it is not possible to prevent an external light from being reflected in the surface of the display due to a fact that the surface of it is almost flat.
Furthermore, a non-glare film of a conventional type as described above has a problem that the visibility of a display screen is degraded due to occurrence of glittering called face-glare (scintillation) on the surface of a, film.
A haze value is used as one of criteria for evaluating such a non-glare film, and there is a problem that lowering the haze value of a surface makes glare feeling called face-glare stronger and raising the haze value to solve this makes an image whitish as a whole and lowers it in black density and thereby degrades the image in contrast. On the other hand, when lowering the haze value to remove the whitishness, a problem happens that what is called reflecting-in and glare feeling result in increasing.
The present invention has been performed in consideration of the above-mentioned existing problems, and an object of the invention is to provide a non-glare film capable of suppressing degradation of contrast and preventing face-glare, reflecting-in and whitening when it is attached onto a display surface, and a polarizing device using the same film and a display device using the same non-glare film or polarizing device.
The present invention is based on the knowledge that in case of forming a non-glare film by laminating a non-glare layer composed of a light transmissive resin containing a light transmissive diffusing material having a refractive index different from the light transmissive resin, when the surface haze value to of the rugged surface of the non-glare layer meets xe2x80x9c7 less than hs less than 30xe2x80x9d and the internal haze value hi by internal diffusion of said non-glare layer meets xe2x80x9c1 less than hi less than 15xe2x80x9d, it is possible to make small the particle diameter of the light transmissive diffusing material and make better the display quality of, for example, a liquid crystal display and the like.
The present invention attains the above-mentioned object by a non-glare film which has a non-glare layer laminated onto at least one of the surfaces of a light transmissive base film, said non-glare layer comprising a light transmissive resin containing a light transmissive diffusing material being different in refractive index from the light transmissive resin, wherein the surface haze value hs on a rugged surface of this non-glare layer meets xe2x80x9c7 less than hs less than 30xe2x80x9d and the internal haze value hi by internal diffusion of said non-glare layer meets xe2x80x9c1 less than hi less than 15xe2x80x9d.
And said non-glare layer may have further a low refractive index layer laminated onto said non-glare layer, said low refractive index layer being lower in refractive index than said non-glare layer.
Moreover, said low refractive index layer may be formed out of a silicon-containing vinylidene fluoride copolymer.
And said silicon-containing vinylidene copolymer may be a polymer composed of a fluorine-containing copolymer which is a copolymer of vinylidene fluoride and hexafluoropropylene and whose fluorine content is 60 to 70 wt %, and a polymeric compound having an ethylene-unsaturated group.
And furthermore, said low refractive index layer may be formed by being coated with a coating film composed of at least said fluorine-containing copolymer and a polymeric compound having said ethylene unsaturated group and then being irradiated with an active energy beam or being heated.
And said low refractive index layer may be formed out of a silicon oxide film have a contamination preventing layer formed on it.
The sum of the surface haze value hs of the rugged surface of the non-glare layer in said non-glare film and the internal haze value hi caused by internal diffusion in said non-glare layer may be equal to or less than 30.
And the difference xcex94n in refractive index between the light transmissive resin and the light transmissive diffusing material in said non-glare layer may meet xe2x80x9c0.01xe2x89xa6xcex94nxe2x89xa60.5xe2x80x9d and the average particle diameter d of the light transmissive diffusing material may meet xe2x80x9c0.1 xcexcmxe2x89xa6dxe2x89xa65 xcexcmxe2x80x9d.
And the light transmissive resin in said non-glare layer may be at least one of a thermosetting resin and an ionizing-radiation hardening resin, and said light transmissive diffusing material may be a type of organic fine particles.
And said organic fine particles may be styrene beads.
The transparent base film in said non-glare film may be formed out of one of a triacetate cellulose film and a polyethylene terephthalate film.
And a transparent conductive layer may be put between the transparent base film and the non-glare layer, and a conductive material may be contained in the non-glare layer.
The present invention related to a polarizing device attains the above-mentioned object by a polarizing device comprising one of said non-glare films and a polarizing plate which is laminated onto the opposite surface of said transparent base film to said non-glare layer of this non-glare film so as to direct its observe surface face to the said opposite surface to said non-glare layer side.
And it is allowable to apply a saponification process to the opposite surface of said transparent base film to said non-glare layer and the surface of said non-glare layer and then laminate a polarizing plate onto the surface of said transparent base film.
The present invention related to a display device attains the above-mentioned object by a display device comprising a display panel which has a plurality of pixels and forms an image by a fact that each pixel transmits or reflects light, and one of said non-glare films provided on the display surface of this display panel.
And the present invention attains the above-mentioned object by a display device comprising a display panel which has a plurality of pixels and forms an image by a fact that each pixel transmits or reflects light, and a polarizing device as described above which is provided on the display surface of this display panel.